An operator may have difficulty visually determining if a group of performance variables is compliant by looking at conventional gauges or other indicators. For example, each and every gauge in the group may need to be read serially, individually and compared to an optimum range to determine if the group of performance variables is compliant. Accordingly, there is a need for a displaying performance variables such that a user can rapidly determine whether or not the variables are collectively compliant. Further, there is need for readily, visually monitoring the relationship between the performance variables.